Liner Panel Having Barrier Layer

ABSTRACT

A cargo trailer includes a floor, a roof and a side wall extending vertically upward between the floor and roof. The side wall includes a substantially gas impermneable outer liner panel and a substantially gas impermeable inner liner panel. The inner liner panel includes at least one glass and polymer layer and one gas impermeable barrier layer. The inner liner panel can also be used to form the roof and replace the outer liner panel.

FIELD OF THE INVENTION

The present invention relates to thermal-insulated walls and moreparticularly to a thermal-insulated wall having a gas impermeablecomposite liner panel.

BACKGROUND OF THE INVENTION

Thermal insulated cargo vehicles, such as van-type trailers, straighttrucks (for example, trucks below Class 8 having bodies built onto truckchassis) and cargo containers, are known. In general, it is desirablethat the bodies defining the cargo compartments of such vehicles havewall constructions that balance strength, rigidity and thermalperformance. The present invention recognizes this need and provides agas impermeable liner panel that reduces degradation of thethermal-insulating properties of a vehicle or other structure.

BRIEF SUMMARY OF THE INVENTION

The present invention recognizes and addresses considerations of priorart constructions and methods and provides a substantially gasimpermeable composite liner panel for use in a thermal-insulated wallconstruction. The liner panel comprises at least one gas impermeablebarrier layer and at least one structural polymer resin layer disposedcoplanar and attached to the barrier layer to form a laminate linerpanel. The polymer resin can be polypropylene, and the gas impermeablebarrier layer can be a metallized polyester film. An adhesive film layeris placed intermediate the barrier layer and the at least one structuralpolymer resin layer to attach these layers together. The gas impermeablebarrier layer could also be formed from metallized polypropylene film ormetal foil. The liner panel can also include a scrim layer that providesa rough surface and a polypropylene film layer that provides a smoothfinished surface. A second structural polymer resin layer can be addedto the composite panel to provide increased thickness for added strengthand toughness. The laminate can be used to form a thermal insulated wallhaving a polyurethane foamed gas impregnated.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one or more embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendeddrawings, in which:

FIG. 1 is a side elevation view of a prior art insulated cargo containerand chassis that may be attached to a tractor for transport over ahighway;

FIGS. 1A and 1B are respective rear and front elevation views of theprior art container and chassis of FIG. 1;

FIG. 1C is a perspective view of a prior art trailer that may beattached to a tractor for transport over a highway;

FIG. 2 is a sectional elevation view of a side of the prior art trailerof FIG. 1C;

FIG. 3 is a perspective view of a prior art thermal wall panel used toconstruct the thermal container of FIG. 1 and the trailer of FIG. 1C;

FIG. 3A is a detailed view, shown in cross-section, of the prior artthermal wall panel of FIG. 3 taken at region 3A;

FIG. 4 is a graphical representation of thermal properties of differentthermal container wall constructions;

FIG. 5 is a perspective view of a woven thermoplastic and glasscomposite material used to form a thermal wall in accordance with anembodiment of the present invention;

FIG. 5A is a detailed view of the thermoplastic material of FIG. 5;

FIG. 6 is a schematic illustration of an apparatus for forming a linerpanel in accordance with an embodiment of the present invention;

FIG. 7 is a perspective view of an embodiment of a thermal wall usingthe liner panel constructed in FIG. 6;

FIG. 7A is a detailed view, shown in cross-section, of the thermal wallof FIG. 7 taken at region 7A;

FIG. 8 is a perspective view of the thermal wall of FIG. 7, viewing theopposite side from that shown in FIG. 7;

FIG. 9 is a partial perspective view of the apparatus of FIG. 6 showingthe formation of the liner panel of FIG. 8;

FIG. 10 is a schematic illustration of an apparatus for forming a linerpanel in accordance with an embodiment of the present invention;

FIG. 11 is a perspective view of a liner panel in accordance with anembodiment of the present invention;

FIG. 12 is an elevation view of a liner panel in accordance with anembodiment of the present invention;

FIG. 13 is a sectional elevation view of a thermal wall in accordancewith an embodiment of the present invention;

FIG. 13A is a sectional elevation view of a side of a trailer includingthe thermal wall of FIG. 13;

FIG. 14 is an elevation view of a liner panel in accordance with anembodiment of the present invention;

FIG. 15 is a sectional elevation view of a side of a trailer includingthe liner panel of FIG. 14;

FIG. 16 is an elevation view, shown in cross-section, of a liner panelin accordance with an embodiment of the present invention;

FIG. 16A is an elevation view, shown in cross-section, of a liner panelin accordance with an embodiment of the present invention;

FIG. 17 is a perspective view of an embodiment of a thermal wall usingthe liner panel constructed in FIG. 12;

FIG. 17A is a detailed view, shown in cross-section, of the thermal wallof FIG. 13.

Repeat use of reference characters in the present specification anddrawings is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION

Reference will now be made in detail to presently preferred embodimentsof the invention, one or more examples of which are illustrated in theaccompanying drawings. Each example is provided by way of explanation ofthe invention, not limitation of the invention. In fact, it will beapparent to those skilled in the art that modifications and variationscan be made in the present invention without departing from the scopeand spirit thereof. For instance, features illustrated or described aspart of one embodiment may be used on another embodiment to yield astill further embodiment. Thus, it is intended that the presentinvention covers such modifications and variations as come within thescope of the appended claims and their equivalents.

FIGS. 1, 1A and 1B illustrate a prior art (insulated but notrefrigerated as shown) cargo container 10 having a floor 12, two sidewalls 14 and 16 and a roof 18. Each side wall is identicallyconstructed. Two top rails 20 attach roof 18 to side walls 14 and 16,respectively, and two bottom rails 22 connect floor 12 to the sidewalls. Once assembled, the roof, floor and side walls form a containerhaving a generally rectangular cross-section when viewed from the rear(FIG. 1A). The distance between opposing inner surfaces of side walls 14and 16 is generally greater than ninety inches, and the distance betweenouter surfaces of the opposing side walls is generally less than 110inches.

The container includes a forward end wall 26 and a rearward end frame28. Two doors 30 at the container's rearward end are pivotally connectedto rear end frame 28. The container rests on a chassis formed by one ormore longitudinal beams extending between retractable legs 24 and aplurality of axled wheels 34. The wheels support the container'srearward end, and facilitate the container's movement, when thecontainer, supported by the chassis, is coupled to a tractor (notshown).

FIG. 1C illustrates a prior art refrigerated van type trailer 11 havinga floor 12, two side walls 14 and 16 and a roof 18. Each side wall isidentically constructed. Two top rails 20 attach roof 18 to side walls14 and 16, respectively, and two bottom rails 22 connect floor 12 andthe trailer's deck structure to the side walls. The trailer includes aforward wall 26 and a rearward end frame 28. Two doors (not shown) atthe trailer's rearward end are pivotally connected to the rear endframe, although it should be understood that a roll-type door may alsobe used. As with container 10 (FIG. 1), the assembled trailer defines aninterior cargo compartment defined by the assembled side walls, forwardwall, rear doors and roof. The distance between opposing inner surfacesof side walls 14 and 16 is generally greater than ninety inches, and thedistance between outer surfaces of the opposing side walls is generallyless than 110 inches. A refrigeration unit 29 mounted in forward wall 26outputs conditioned air to the interior cargo compartment. The terms“side wall,” “front wall” and “rear door” are used separately in thepresent discussion for purposes of explanation, and it should beunderstood that the term “side wall,” as used herein, may refer to anyside wall, front wall or rear doors of an insulated or other structure.

The difference between a container and trailer is that the trailer hasan integral chassis and suspension, and does not have frames that areconfigured to permit the lifting and stacking of the container, asshould be understood in this art. In other words, as should be wellunderstood in this art, the container is a box that is placed on andremovably attached to the longitudinal I-beam type chassis, as shown inFIG. 1. FIG. 2 provides a partial sectional view of the roof, floor andone of the side walls of a thermal enclosure for use in formingcontainer 10 or trailer 11.

Referring to FIG. 2, top rail 20 connects wall 14 to roof panel 18. Toprail 20 is formed from extruded aluminum and defines a U-shaped channel36 having an upper flange 38 extending outwardly over a vertical leg 40that extends from upper flange 38 to a lower horizontal flange 48. Theterms “inward” and “outward,” as used herein, are defined relative tothe container's interior space indicated at 46. Moreover, the term “roofpanel,” as used herein may refer to a single continuous panel, or to aplurality of discrete panels that are attached together, that form theroof of trailer 10. Horizontal flange 48 extends outward from the loweredge of vertical leg 40, and a vertical leg 50 extends downward fromflange 48. Side wall 14 is received against vertical leg 50 and issecured at 54 by screws, rivets, tapit pins, or any other suitableconnection method. Roof panel 18 is secured to flange 38 at 70 byscrews, rivets, tapit pins, or any other suitable connection method. Anangled bracket 52 having mounting flanges 42 and 44 extends between aninner liner 62 of roof 18 and wall 14. Bracket 52 is secured to the wallat 51 and to the roof at 56 by screws, rivets, tapit pins, or any othersuitable connection method. Once angled bracket 52 is secured in place,an insulating polyurethane rigid foam core 53 is forced into the channelformed between bracket 52 and rail 20 to insulate any voids between theroof core 58 and the wall core 94.

Roof panel 18 includes a thermoset plastic rigid urethane foam core 58between upper and lower liner panels 60 and 62. Upper liner panel 60 maybe formed by an aluminum sheet that is preferably about 0.040 inchesthick, and lower layer 62 may be a thermoset fiberglass reinforcedplastic sheet that is preferably about 0.080 inches thick. The lowerliner panel has an extension 64 that extends beyond foam core 58 byabout 0.50 inches, and the upper liner panel has an extension 66 thatextends beyond the core by about 2.25 inches. Extension 64 abuts bracket52, and upper liner panel extension 66 extends over and on rail flange38. A cover 68 covers the edges of flange 38 and upper liner panelextension 66. Cover 68 and liner panel extension 66 are attached at 70to flange 38 by screws, rivets, tapit pins, or any other suitableconnection method. A sealant (not shown) may be placed over the rivetand seam locations to inhibit moisture intrusion into the inner foamedareas.

Bottom rail 22 connects side wall 14 to the floor system or deckstructure and includes a vertical leg 72 and a horizontal leg 74. Therail may be formed from any suitable material such as extruded aluminum.A scuff plate 78 fits over the lower edge of wall 14, and the scuffplate bottom edge overlaps a corrugated floor surface 88. Wall 14 isfastened to vertical leg 72 at 76 by screws, rivets, tapit pins, or anyother suitable connection method. A plurality of transverse crossmembers 82 (one of which is shown in FIG. 2) extend under the floor andare riveted or bolted to and between the two bottom rails 22 at 84. Thetransverse cross members, in conjunction with the wheels and retractablelegs form the trailer s chassis. The floor includes an insulatingpolyurethane rigid foam core 90 disposed between a fiberglass sub-floor86 and upper extruded aluminum decking 88.

Referring to FIG. 3, the side walls of the thermal compartment shown inFIG. 1 and 1C are formed from a plurality of skins (FIG. 1) connected at92 by screws, rivets, tapit pins, or other suitable connection method.FIG. 3 shows a pair of adjacent skin panels 14 a and 14 b that overlapat their edges and are secured together by rivets 92. The outer skin isfit together in this manner to form a continuous outer skin. Toconstruct a thermal insulated wall panel, an inner liner panel 96 isspaced apart from outer skin 98, and thermal insulating foam is blown orpoured into the channel between the outer skin and the inner linerpanel. Fitted together in this manner, the outer skin, foam core andinner liner panel provide structural support to the side wall betweenthe top and bottom rails, forming a “frameless” (or “monocoque”)construction. In a post and panel construction, by contrast, each panelis attached by rivets or other suitable means to vertical posts thatextend between the trailer's top and bottom rails. A post is disposedbetween each pair of adjacent panels so that both panels attach to thepost. In either a composite panel or a sheet and post construction, thetop and bottom of wall 14 are connected to top and bottom rails 20 and22.

Outer skin 98 may be formed from plastic, aluminum, stainless steel orother metal alloy, and inner panel liner 96 typically is formed from athermoset or thermoplastic glass reinforced composite. Examples of innerliner panel materials include polyester-based thermoset composites, suchas Kemlite LTR or ARMORTUF available from Kemlite Company of Joliet,Illinois, and polypropylene-based thermoplastic materials, such asBULITEX available from US Liner Company of Ambridge, Pa. As should bewell understood, “thermoset” refers to a class of polymers that, whencured using heat, chemical or other means, change into a substantiallyinfusible and insoluble material. Once cured, a thermoset material willnot soften, flow, or distort appreciably when subjected to heat and/orpressure. “Thermoplastic,” on the other hand, refers to a class ofpolymers that can be repeatedly softened by heating and hardened bycooling through a temperature range characteristic of the particularpolymer and that in the softened state can be shaped. Whether thermosetor thermoplastic, the glass reinforced composite of liner panel 96 isgenerally known to be gas permeable with respect to the gas blowingagents entrapped in the foamed polymer used to form the insulating core.

Liners made from such gas permeable polymers are relatively lighter thanliners made from sheets of known gas impermeable materials such aswrought aluminum or stainless steel. For example, a 0.020 inch thickstainless steel liner panel weighs about 0.84 lbs/sq.ft., and a 0.040aluminum liner panel weighs about 0.56 lbs/sq.ft. In contrast, theKemlite 0.090 inch, 25% glass material weighs about 0.51 lbs/sq.ft., andKemlite's ARMORTUF® 0.050 inch liner panel weighs about 0.40 lbs/sq.ft.Typical thermoplastic liners, such as 0.100 inch BULITEX® and a 0.050inch BULITEX, weigh about 0.78 lbs/sq.ft. and 0.32 lbs/sq.ft.,respectively. Thus, while known thermoset and thermoplastic linermaterials do not have the gas impermeability of metals, they aregenerally advantageous over metals since they are typically lighter andresilient.

FIG. 3A shows a detailed cutaway view of a portion of side wall panel 14a. Outer liner panel 98 is an aluminum layer about 0.04 inches thick,and inner liner panel 96 is a glass reinforced polymer compositematerial with a thickness in the range of about 0.060-0.100 inches.Polyurethane core 94 is preferably about 1.50 inches thick and tends toform a series of closed cells, in each of which is embedded a lowthermal conductivity gas 100 such as CFC 141 b, HCFC 22 or HFC 134a. Gas100 is introduced into the core cells when the polyurethane foam in aliquid state is poured in place and reacts to form a rigid polyurethaneinsulating foam. As represented in FIG. 3A, impregnated gas 100 isdistributed throughout the solid core material and generally representsapproximately 98% of the core material, the remainder being thepolyurethane cell walls surrounding the gas. It should be understood inthis art that other thermal insulating core materials may be used toform the thermal insulated wall panels, such as STYROFOAM® (styrenicfoams), PVC foams, or fiberglass batting.

Low conductivity gas 100 improves the thermal properties of wall 14, butover time the thermal insulating properties of side wall 14 degrades.Several factors influence the thermal conductance of the polyurethanefoam core, for example the thermal conductivity of the cell gas, thermalconductivity of the cell material, convection of the cell gas and solarradiation. For purposes of this discussion, the main cause of thermaldegradation in the core material results from migration (diffusion) ofthe cell gas out of the core and into the atmosphere (“out-gassing”),moisture (water vapor) and “air” (mostly C0 ₂) intrusion into theenclosed foam area, and from UV degradation of the polyurethane foamcore.

Because the cell walls and inner liner panel 96 are gas permeable,out-gassing occurs over time as low-thermal conductivity gas 100 passesthrough both the cell walls and the inner liner panel, as indicated at100 a and the arrow identified as 100 b. The loss of low thermalconductivity gas 100 significantly degrades the thermal insulationperformance of the polyurethane foam over time.

In addition to out-gassing, water vapor intrusion through the polymerliner panel also degrades the thermal insulation performance of thepolyurethane foam. That is, the polymer liner panel may have microscopicholes in the laminate due to manufacturing imperfections. Thus, forexample, during pressure cleaning of the interior surface of the traileror thermal compartment, water seeps through the holes or imperfectionsand impregnates the polyurethane foam core. Water absorption of onepercent of the volume increases the thermal conductivity byapproximately 0.0015 W mK, thereby increasing the thermal conductivityof the polyurethane core.

Some materials absorb UV light more readily than other materials, forexample rubber, vinyls, gelcoat fiberglass, and many other plastics.Materials that readily absorb UV light are quickly damaged. For example,the performance of most thermoplastic materials depends largely on theirmolecular structure. A tough, resilient material will generally exhibita structure in which the molecules are arranged in long, chain-likeconfigurations. The absorption of UV light causes the molecular chainsto break up (cleave) into shorter chains. This process, known asphotodegradation, leads to bleaching (fading), discoloration, chalking,brittleness and cracking—all indications of UV deterioration. The bondcleavages resulting from UV absorption cause the formation of“radicals.” Each free radical can trigger a chain of reactions (in thepresence of air), leading to more bond cleavages and destruction. Theseoxidizing chain reactions require no further UV exposure, just thepresence of air. Thermoset plastic materials are effected by UV in asimilar manner to thermoplastics. Thus, UV light causes the polymers tobreak down expediting the effects of out-gassing.

Because metal is naturally gas, moisture and UV impermeable,out-gassing, water intrusion and UV degradation does not generally occurthrough the metal outer skin panel unless there are areas in the skinthat have been compromised, such as by tears, holes or seams.Polyurethane foam cores and the causes of thermal degradation should beunderstood in this art and are therefore not discussed in detail herein.Further information may be found, for example, in the PolyurethaneHandbook, published by Hanser Publishers and distributed by MacmillanPublishing Co., Inc. of New York, N.Y.

FIG. 4 is a graphical representation of the thermal insulationperformance of various thermal wall constructions over time.Conductivity curve 104 represents a gas impregnated urethane coresandwiched between two gas permeable liner panels, such as panels formedfrom ARMORTUF or BULITEX. Conductivity curve 106 represents a gasimpregnated urethane core sandwiched between one gas permeable linerpanel and one gas impermeable liner panel, such as the prior art wall ofFIG. 3. Finally, conductivity curve 108 represents a gas impregnatedurethane core sandwiched between two gas impermeable liner panels, suchas the wall construction described herein. The graph illustrates thatthe majority of thermal degradation occurs early in the useful life ofthe thermal-insulated trailer, which is approximately 10-12 years. Curve108 illustrates that minimal degradation, about 5 percent, in thermalinsulation occurs when both liner panels are formed from a gasimpermeable material. That is, if both the inner and outer liner panelsare formed from gas impermeable material, a low thermal conductivity ismaintained, and little gas is leaked through joints in the inner orouter wall surfaces. Thus, in comparing curve 108 to curve 106, anapproximately 20% greater thermal degradation occurs when one of theliner panels is formed from a gas permeable material, and in comparingcurve 108 to 104, an approximately 35% greater thermal degradationoccurs when both of the liner panels is formed from a gas permeablematerial.

One suitable gas, moisture and UV impermeable wall liner that overcomesthe disadvantages of prior art thermoplastic, thermoset, and metal linerpanels may be formed by a lamination process. As should be understood, alaminate is made by bonding together two or more sheets of distinct,usually man-made materials to obtain properties that cannot be achievedby the component materials acting alone. In the presently describedexample, the liner is formed through a consolidation process thatincludes heating and compressing multiple layers of thermoplastic and/orthermoset materials and then cooling the resultant laminate. In thisexample, the laminate has at least one gas impermeable barrier layer andat least one layer of a structural polymer material that provides thewall panel's strength and rigidity. The term “structural polymer” asused herein means a polymer that includes a reinforcement material suchas fibers or a polymer that exhibits increased strength and toughness asa result of its molecular structure and the resulting intermolecularattraction forces. That is, by aligning the polymer molecules in aparticular orientation, the molecule chains and intermolecularattraction forces increase the strength and toughness of the polymerwithout having to add a reinforcing material to the polymer. One exampleof such orientation is biaxial molecular orientation, which is wellknown by one skilled in the art.

FIGS. 5 and 5A illustrates one example of a material that may be used toform the structural polymer layer. A fabric 110 is formed from aplurality of woven rovings 112. Each roving 112 is formed from multiplesubstrands of commingled glass fibers 114 and polymer resin 116. Thatis, each roving 112 is comprised of two types of materials, i.e., glassfibers 114 and thermoplastic resin 116, intermingled into a singleroving so that an even distribution of the two materials results. Othertypes of fibers may be used in the structural layer include Kevlar,carbon fiber, or natural fibers. In the preferred embodiment, polymerresin 116 is polypropylene, and each roving is generally long andessentially continuous. A polypropylene resin is a solid polymericmaterial that exhibits a tendency to flow when subjected to heat andpressure, usually has a softening or melting range, and is frequentlyused to bind together reinforcement fibers such as glass fibers. In apreferred embodiment, fabric 110 is a 22 oz./yard² TWINTEX® fabric,which is a 60% glass, 40% polypropylene plain balanced weave and isapproximately 0.20 inches thick prior to consolidation, manufactured bySaint-Goban Vetrotex of Wichita Falls, Kans. Fabric 110 mayalternatively be a non-woven material, for example a needle mat soldunder the name ASGLAWO® by ASGLAWO GmbH of Freiberg, Germany. Thenon-woven mat is made of 30% E-Glass and 70% polypropylene. As should beunderstood, the added fibers are used to provide structural strength andtoughness to the laminate material.

FIG. 6 schematically illustrates a machine 200 that consolidates a matas shown in FIG. 5 with various other layers into a linear laminatepanel in accordance with an embodiment of the present invention. Thatis, machine 200 applies heat and pressure to a multilayer material tofuse the thermoplastic raw materials into a relatively rigid sheet andto achieve a desired density in the laminate. Consolidation does notnecessarily involve high temperatures or pressures, and in one preferredembodiment, consolidation can be achieved at a temperature between200-225 degrees centigrade and a pressure range of 150 to 260 N-m percentimeter. One suitable consolidation machine 200 is a contact heatoven manufactured and sold by Schott & Meissner GmbH of Germany underthe name THERMOFIX. FIG. 6 should be understood to be a representativeschematic example provided for illustrative purposes, however, and otherconsolidation machines may be used to form the laminate of the presentinvention.

A rack 202 of machine 200 holds multiple rolls of material that are fedinto a pair of guide rollers 204 driven by a lower belt 206 so that thelayers are carried down stream into the machine on the lower belt. Eachlayer is coplanar with the adjacent upper and/or lower layers and isgenerally of the same length and width so that the resultant materialhas uniform properties throughout.

The raw materials that form the laminate are stored on large rolls inrack 202. FIG. 6 illustrates seven materials being fed coplanar intoconsolidator 200: a polypropylene surface film 222, woven fabricmaterial 110, an adhesive film 224, a gas impermeable barrier film 226,a second adhesive film 224 a, a second woven fabric 110 a and a scrimlayer 228. Each layer is approximately the same width and length as theother layers so that the resultant composite laminate is uniform fromend to end. The consolidating machine of FIG. 6 can form a laminatesheet with a width of about 115 inches, and in a preferred embodiment,the laminate is about 96 to 100 inches wide.

In one preferred embodiment, barrier film 226 is formed from a thinlayer of polyester thermoset material having a thin layer of metaldeposited on its surface. The metal is deposited by placing a substrate(PET film) in to a chamber containing an atomized fog of molten aluminumvapor. As the substrate is uncoiled and removed from the vacuum chamber,a thin layer of aluminum is deposited onto the substrate. A suitablebarrier film is a 92 gauge MB30 metallized polyethylene terephthalate(PET) film (manufactured and sold by Toray Plastics, Inc. of FrontRoyal, Va.), which has an aluminum layer at a thickness of about 24 μm.Although it is known that an aluminum layer is generally effective atproviding a gas and moisture impermeable barrier at thicknesses greaterthan 50 μm, the 24 μm aluminum layer of the PET film provides aneffective gas (as shown in FIG. 4) and moisture barrier

Because fabrics 110 and 110 a generally will not directly adhere to thethermoplastic or metal sides of film 226, adhesive films 224 and 224 a,which are capable of bonding to both the thermoset material of barrierfilm 226 and to the thermoplastic material of the mats, are disposedbetween film 226 and mat 110 and between film 226 and mat 110 a.Suitable adhesive films include a UAF polyurethane adhesive film and aPAF polyester based heat activated adhesive film, each manufactured byAdhesive Films, Inc. of Pine Brook, N.J. It should also be understoodthat other forms of adhesives can be used to bond barrier film 226 tomats 110 and 110 a. For example, spray adhesive can be applied to thebarrier film prior to being fed into guide rollers 204. In anotherexample, barrier film 226 can be roll coated with adhesive prior tobeing fed into guide rollers 204. Barrier film 224 may also be modifiedto bond directly to mats 110 and 110 a.

Surface film layer 222 forms a smooth protective outer layer to enhancecosmetic appeal and add longer life to the laminate. A suitable surfacefilm layer 222 is XAMAX FLOVEILII® style 620 thermoplastic copolymerdistributed by XAMAX Industries of Seymour, Conn. In the preferredembodiment, surface layer 222 is approximately 6 mils thick prior toconsolidation.

Scrim layer 228 provides a relatively rough surface to which thepolyurethane foam core may readily adhere. One suitable scrim materialis ECOVEIL® PBT, which is a visible pattern bonded polyester distributedby XAMAX Industries, Inc. In the preferred embodiment, scrim layer 228is approximately 6-8 mils thick prior to consolidation.

It should be noted that the above described materials are used in onepreferred embodiment but that other suitable materials may be used.Other suitable gas impermeable barrier materials include, for example,metallized polypropylene films and metal foils, such as aluminum foil.In an embodiment employing foils, the laminate would include adhesivelayers 224 and 224 a to bond mats 110 and 110 a to the foil layer.Alternate scrim materials are spunlaced polyester manufactured byPrecision Fabrics Group, Inc. of Greensboro, N.C., glass fiber materialor other rough material that does not melt or that melts at atemperature substantially higher than the other materials.

Returning to machine 200, belt 206 faces opposite a belt 208 so that thelayers of material are sandwiched between the belts. Belts 206 and 208are coated with a non-adherent releasing film surface, for examplestainless steel, TEFLON or other suitable material, so that the laminatematerial easily releases from the belt at the end of the machine.

Belts 206 and 208 pass the layers through a heating stage 210, acalendar stage 212 and a cooling stage 214. Heating stage 210 includespan type heating elements 216 that carry heated oil to conduct heatthrough belts 206 and 208 and into the input materials. The heating ofmats 110 and 110 a, polypropylene surface film layer 222 and scrim layer228 causes the thermoplastic materials to flow so that added pressure bybelt rollers 218 in calendar section 212 causes the scrim and surfacefilm layers 228 and 222 to embed or mechanically bond with thepolypropylene and glass fibers of the adjacent mat layers 110 a and 110,respectively. The heat also causes adhesive films 224 and 224 a to meltor activate, enabling thermoplastic materials 110 and 110 a to bond tothe polyester thermoset and metallized barrier layer 226.

The temperature of heating stage 210 is computer controlled to a levelthat causes the materials to flow and bond, but not liquefy. The controlof pan type heating elements should be well understood and is,therefore, not discussed in detail herein. “Flow” is defined as thepoint where a thermoplastic reaches a semi-liquid state. Because not allthermoplastic materials reach a state of flow at the same temperature,the layered material should be heated to the highest flow temperature ofthe materials. Fabric 110 requires a consolidation temperature of atleast 205 degrees centigrade and not more than 250 degrees centigrade toprevent the material from burning if the machine speed is very slow.Thus, in the preferred embodiment, the layered material is heated to atemperature of about 225 degrees centigrade so that all thermoplasticlayers begin to flow, thereby allowing the layers to properly bond. Asshould be understood in this art, the ideal consolidation temperaturevaries depending on the machine speed, the number of layers beingconsolidated and the flow characteristics of the polymer.

Belt rollers 218 of calendar stage 212 apply sufficient pressure to thematerials so that they bond to form a generally uniform laminate 201.The amount of pressure depends on the temperature of the input materialsand the desired thickness of output laminate 201. In a preferredembodiment, the pressure exerted on the layered material is about 20-22kN.

Once the materials have been consolidated, the soft pliable laminate 201solidifies at cooling stage 214. The cooling stage employs cooling pans220 that carry water to dissipate heat retained in the laminate. Thetemperature of the cooling water varies between 10 and 20 degreescentigrade depending on the number of layers in the laminate and thespeed of the machine so that in a preferred embodiment, the laminate iscooled to a temperature of about 30 degrees centigrade. At 30 degreescentigrade, the laminate panel is stable and will not warp.

Consolidating machine 200 is able to form a continuous sheet of varyingwidth and length of composite material that can then be rolled forstorage. In the preferred embodiment, the laminate is formed in sheetsabout 102 inches wide and 500 feet long. The laminate may then be cutinto desired sizes for gas impermeable liner panels to be used in thewalls of refrigerated trailers, insulated containers, truck bodies orother thermally insulated structures, which may or may not be used inconjunction with vehicles, such as refrigerators, portable coolers,thermal-insulated buildings and walk-in-coolers.

FIG. 7, for example, illustrates a wall panel 300 with a core and outerliner panel as in the panel shown in FIG. 3 but with an inner linerpanel 304 that is a section cut from laminate 201 so that thegas-impregnated core is sandwiched between two gas, moisture andUV-impermeable liner panels. Referring to FIG. 7A, outer liner 302 is agas, moisture and UV impermeable material such as aluminum, steel orother metallic material. Insulated core 306 is formed from gasimpregnated rigid foamed polyurethane similar to that shown in FIG. 3A.Inner liner panel 304 is formed by the consolidation process describedabove and includes a scrim layer 228, a glass reinforced layer 110 a, abarrier layer 226, a second glass reinforced layer 110 and apolypropylene surface film layer 222. Barrier layer 226 provides a gas,moisture and UV impermeable layer that eliminates out-gassing of the lowthermal conductivity cell gas. The metallized film as described abovealso establishes a UV light and moisture barrier that inhibitsdegradation of the wall panel's insulating properties. The glass fiberreinforced layers 110 and 110 a provide desired structuralcharacteristics at a lighter weight than a solid metal liner. Forexample, in a preferred embodiment, composite laminate 201 has athickness of about 0.070 inches and weighs about 0.30 lbs/sq.ft.compared to a 0.040 inch aluminum liner panel that weighs 0.56lbs/sq.ft. Scrim layer 228 provides a rough surface at which to bondliner panel 304 to urethane core 306, and surface film layer 222provides a smooth surface at the cargo area's interior.

Laminate 201 is flexible so that it maybe rolled for storage andshipment. Flexibility is not required, however, particularly where athermoset material is used as the foundation layer. Where a flexible ornon-flexible foundation material is used, the liner panel exhibitsstrength and stiffness within the plane of the liner panel itself.Stiffness is the ability to withstand a load without deforming, whereasstrength is the ability to withstand the force of the load withoutbreaking. By being stiff and strong within the plane of the material,the liner panel may contribute structural stability to a wall panel of acargo vehicle or other structure in which a gas or vapor impermeablebarrier is desired. Thus, for example, laminate 201 maybe used in a wallstructure as shown in FIG. 7 in the side walls, front wall and roof of aframeless trailer as described above. A typical wall panel may need towithstand in-plane stresses within a range of 0.00 to 30,000 lbs/inch²of liner material from blows resulting from the loading and unloading ofcargo.

Preferably, as in the case of laminate 201, the liner is “tough” and“resilient” in the direction normal to the liners plane. That is, it isstrong, deformable and exhibits elasticity in a direction normal to theliner's face so that the liner is capable of regaining its originalshape or position after deforming by a blow normal to the line'ssurface, for example as received from a lift truck, hand trucks, orfalling cargo during loading or unloading of a trailer or cargocontainer. Thus, the liner panel should not be brittle.

As should be understood in this art, toughness is a characteristic ofthe material, whereas stiffness and strength are characteristics of thematerial and it geometry. Thus, because of liner panels planar geometryand its material characteristics, laminate 201 exhibits in-planestrength and stiffness and transverse toughness. More specifically, theglass fibers embedded in the foundation layer 110 and 110 a of laminate201 provide strength characteristics in both the in-plane and transversedirections, while the layered polymer composition provides transverseresiliency. The degree of desired in-plane stiffness and strength, andtransverse flexibility, of a particular liner panel will depend upon howa particular liner panel such as laminate 201 is used.

Still referring to FIG. 7, it should be understood that while outerliner panel 302 and inner liner panel 304 are gas impermeable,out-gassing may still occur from areas where the integrity of the innerand outer liner panels have been compromised. For example, out-gassingmay occur at rivet holes and seams where the wall panels are connectedto adjacent wall panels or posts and/or at the top and bottom rails andat edges of the side wall or roof panels where the core is exposed.Thus, while the material forming the barrier layer is gas impermeable,the resulting liner panel and wall panel may be described as“substantially gas impermeable” due to penetration of the liner panelduring construction of the trailer, container or other structure and/orto the construction of the particular panel. That is, as shown in FIG.4, while curve 108 shows a substantial decrease in thermal degradationcompared to wall constructions for curves 104 and 106, there is stillsome degradation in a wall constructed with two gas-impermeable linerpanels. However, for practical purposes, the degradation is minimal, andthe overall efficiency of the side walls, front wall and/or roof issubstantially improved. Thus, as used herein with respect to a linerpanel or barrier layer, the terms “substantially gas impermeable” meanthat the panel or layer acts as a barrier to the transfer of a gas fromone side of the panel to the other side. In an embodiment of theinvention, a barrier or liner is substantially gas impermeable when thetransfer of low conductivity gas at atmospheric conditions across thebarrier or layer results in a thermal degradation curve approximate thatof curve 108.

Referring again to FIGS. 1A-1C, the side walls, front wall and roof of acargo compartment as shown in the figures may be formed using wallpanels that include laminate 201. For purposes of this discussion, theterm “cargo compartment” refers to the cargo area of a container,trailer or body of a straight truck for use with a wheeled chassis. Forexample, wall panels 14 a and 14 b shown in FIG. 3 may be manufacturedto include the gas-impermeable liner panel as shown in FIG. 7.Therefore, multiple panels can be connected to form the side walls,front wall and/or roof of the container or trailer shown in FIG. 1.Additionally, the walls or roof may be formed from a single continuouspanel that contains few or no seams, thereby reducing the number ofareas that may cause out-gassing. Moreover, in addition to usingcomposite laminate 201 as the inner surface of a wall or roof panel,composite laminate 201 can also be used as the outer liner panel for awall, roof or floor panel to further reduce the overall weight of thecontainer or trailer. The terms “wall panel” and “roof” are usedseparately in the present discussion for purposes of explanation, and itshould be understood that the term “wall panel,” as used herein, mayrefer to any side, top or bottom wall of an insulated or other structurein which a gas and/or vapor barrier is desired.

Whether composite laminate 201 is used as the inner and/or outer linerpanels for a wall or roof panel, the laminate's surface layer forms anexposed surface of the overall structure. Thus, for aesthetic reasons,surface film layer 222 preferably forms a smooth, easily cleanablesurface. However, although most of the outer surface 310 is smooth anduniform, consolidating machine 200 (FIG. 6) forms a repeating surfaceblemish 312 on the outer surface 310 of inner liner panel 304, as shownin FIG. 8, formed by a seam 314 in belts 206 and 208, as shown in FIG.9. That is, as belts 206 and 208 move the layered material throughconsolidator 200, belt splices 314 and 314 a contact the outer and innersurface of the laminate and imprint blemish 312 at a regular frequency.Thus, the outer surface of inner liner panel 304, as well as the innersurface, contains a repeating seam imprint. One method of eliminatingthe blemish is to trim and throw away that portion of the compositelaminate.

In an alternate embodiment of the consolidating system shown in FIG. 10,however, consolidating machine 200 is shown along with a modifiedmaterial rack 402 that holds 15 rolls of input material. Similar to theconsolidation process described above, a first multilayer group 400 ofmaterial includes a surface film layer 222, a glass reinforcedpolypropylene layer 110, an adhesive layer 224, a barrier layer 226, asecond adhesive layer 224 a, a second glass reinforced polypropylenelayer 110 a and a scrim layer 228. The layers are ordered so that scrimlayer 228 contacts lower belt 206 while surface film layer 222 contactsa release material 404 also held on rack 402. A second multilayer group410 includes a veil layer 412, a glass reinforced polypropylene layer414, an adhesive layer 416, a barrier layer 418, a second adhesive layer416 a, a second glass reinforced polypropylene layer 414 a and a scrimlayer 420. The layers are ordered so that scrim layer 420 contacts upperbelt 208 while surface layer 412 contacts release material 404. That is,release material 404 is sandwiched between first multilayer group 400and second multilayer group 410 as they pass through consolidator 200.Consequently, belts 206 and 208, and their respective belt seams, nevercontact respective surface film layers 222 and 412. As a result, theconsolidation machine does not impart a blemish on the surface 310 ofliner panel 304 that is exposed to the interior of the finishedinsulated structure, and output production is doubled. Moreover, aslaminates 201 and 201 a exit the consolidation process, release film 404may be wound onto a roller so that it can be stored and reused in alater consolidation. In a preferred embodiment, the release layer is aMB30 metallized PET film manufactured by Toray Plastics, Inc.Alternatively, the release layer may comprise a metal foil layer or apolymer such as MELINIX polyester produced DuPont Teijin Films U.S.Limited Partnership, 1 Discovery Drive, P.O. Box 411, Hopewell, Va.23860.

It should also be understood that while a first and second materialgroup is discussed above, a third material group may be added in a stillfurther embodiment so that the belt seams do not imprint on any of theveil layers, while output production is tripled. That is, a releaselayer is placed intermediate each multilayered group, and the materialsare ordered, so that the belt seams do not contact the veil layers. Inyet another embodiment, a single material group may be fed intoconsolidator 200 with an additional release layer 404 added on top ofsurface film layer 222. That is, the surface layer would not contact thebelt seam since it is protected by the release layer. Of course, thereis a limit to the number of layers that can be consolidated during agiven pass. For instance, the THERMOFIX® contact heat oven used in theabove-described embodiment allows up to a 3/10 inch thick laminate(s) tobe formed. However, other consolidation machines exist that allow for agreater number of layers that result in a thicker laminate.

It should also be understood that various layers may be eliminated fromthe consolidation process depending on the application of the laminate.For example, fabric layer 110 a (FIG. 6) may be eliminated to reduce thenumber of layers forming laminate 201, although adhesive layer 224 a maybe retained to adhere the scrim layer to the barrier layer. At aminimum, in addition to the barrier layer, the laminate requires atleast one structural layer and one adhesive layer, which may be thebarrier layer.

Besides eliminating an entire layer, portions of a layer can beeliminated or added. Referring to FIG. 11, for example, one-half of mat110 a is eliminated from the top half of the panel to lighten the weightof the overall wall panel structure while providing strength andrigidity at the lower half of the resultant wall panel. A shim layer 602can be placed on top of layer 222 to cover the area where mat 110 a wasremoved so that proper consolidation can be achieved. That is, shim 602fills the void in the layered material so that the layered group has auniform thickness as it is fed into machine 200. Moreover, as shown inFIG. 12, two laminate sheets can be formed by the process described inFIG. 10 when one-half of mat 110 and mat 414 is eliminated. In doing so,the layers are oriented so that a shim layer is not necessary. That is,one group of material is positioned so that half layer 110 is orientatedto the opposite side of half layer 414 so that each half layer acts as ashim for the other group of material. Once consolidated, the twolaminates separate due to release layer 404 and each has a portion oflaminate having a thicker cross-sectional area at the bottom of theresultant laminate.

Referring back to FIG. 2, scuff plate 78 prevents damage to the lowerportion of the wall when cargo is loaded into or removed from thetrailer. If provided, the protective scuff plate generally protrudesinto an otherwise useable storage area within the trailer. Thus, a scuffplate formed integral to the laminate inner liner panel provides theneeded strength and rigidity to the wall while increasing useablestorage area in the trailer. As shown in FIG. 13, an integral scuffplate may be formed by providing multiple layers of mat 110 at the lowerone to two feet of the laminate. For example, during the consolidationprocess, multiple layers of mat 110 a or 110 placed at the bottom edgeportion of laminate 201 increases the thickness of the liner panel whereit is most susceptible to impact. That is, multiple layers of mat 110are placed proximate the lower portion of laminate 201 so that athickened laminate portion forms an integral scuff plate 78, whichprotrudes into interior 46 of the trailer. A shim layer, as described inFIGS. 11-12 is used during the consolidation process to fill voidscreated by the partial layers. As shown in FIG. 13A, the laminate havingan integral scuff plate can also be used to form a thermal insulatedwall in a trailer or container.

In an alternative embodiment, where cargo space is an issue, multiplelayers of 110 a are used proximate the lower portion of laminate 201 sothat the thickened scuff plate extends into the core and the outersurface of the liner panel is linear from top to bottom. In addition toplacing extra glass reinforced polymer material at the bottom portion ofthe laminate, additional layers can also be added to the top portion ofthe laminate to provide added strength and stability at attachmentpoints. As shown in FIG. 14, an additional layer of mat 110 a at theupper and lower one-third of the structure provides additional strengthand rigidity at critical areas of the wall panel, such as where theyconnect to the upper and lower rails. A shim 602 is placed intermediatethe extra layers so that the layered material has a uniform thickness asit is fed into machine 200. As shown in FIG. 15, a liner panel withreinforced upper and lower portions can be used in a wall structure fora trailer and container. Besides reinforcing the upper and lower edgesof the laminate, a reinforcing layer may also be located approximate themiddle of the laminate to allow for structural attachments such as alogistic track or partition walls.

The majority of the above discussion of adding a gas and moisturebarrier layer to a laminate panel is directed to panels formed byheating and pressing multiple layers of thermoplastic and thermosetmaterials together. However, gas and moisture barrier layers may also beadded to thermoset liner panel constructions. Referring to FIG. 16, forexample, a glass reinforced thermoset liner panel 500 may be formed inany height and length. First, a glass reinforced thermoset layer 501 isformed using well known methods in the art, such as by pouring athermoset material onto a moving belt and scattering glass fibersthroughout the material. Next, a layer of aluminum or other metal 502 isbonded to an outer surface of glass reinforced thermoset layer 501 byspraying, sputtering or adhesively bonding the metal to the surface.This may be accomplished during the curing process or after thethermoset material has cured. For example, as shown in FIG. 16A, liquidaluminum 503 is sprayed onto one side of thermoset layer 501 by asprayer 505 to form a uniform metallized layer 502. If, instead, abarrier film is used, a spray adhesive can be applied intermediate thebarrier layer and thermoset layer to bond the barrier layer to thesurface of thermoset layer 501. Suitable adhesives for bonding thebarrier layer to the thermoset include acrylic and urethane liquidadhesives. After depositing the barrier layer, a second thermoset layer504 (FIG. 16) can be poured over the barrier layer to sandwich thebarrier layer within the thermoset composite panel. An additionaladhesive layer may be necessary to bond the thermoset layer to thebarrier layer. Other layers can be added to the thermoset composite,such as a scrim layer and a surface layer.

In yet another embodiment, the second layer 504 can be eliminated sothat the barrier layer forms an outer surface of the glass reinforcedthermoset liner panel, as shown in FIG. 16A. A scrim layer 228 (one ofwhich is shown in FIG. 17A) can be bonded to the exposed surface of thebarrier layer to provide a bonding surface for a polyurethane core 306.In addition to scrim layer 228, a surface layer 222 can be added toprovide a desired texture to the outward facing surface of liner panel500. For example, in the preferred embodiment, surface layer 222 is aTEDLAR film layer manufactured by DuPont of Buffalo N.Y.

In yet another embodiment, a thermoset composite panel can be formed byfirst forming two thermoset layers and adhesively bonding the two layersto opposite sides of a metallized barrier layer. For example, twoARMORTUF panels can be adhesively bonded to a metal or foil barrierlayer. As should be understood in the art, other methods exist forforming a thermoset layer and are within the scope of the presentinvention.

FIG. 17, illustrates a wall panel 300 with a core and outer liner panelas in the panel shown in FIG. 7, but with an inner liner panel 506 thatis a section cut from laminate 500. Referring to FIG. 17A, outer liner302 is a gas impermeable material such as aluminum, steel or othermetallic or gas impermeable material. Insulated core 306 is formed fromgas impregnated rigid polyurethane foam similar to that shown in FIG.7A. Inner liner panel 506 is formed by providing a barrier layer 502intermediate a first and second thermoset layer 501 and 504,respectively. The metallized barrier layer also establishes a light andmoisture barrier that inhibits degradation of the wall panel'sinsulating properties. The glass reinforced thermoset layers providedesired structural characteristics at a lighter weight than a solidmetal liner. For example, in a preferred embodiment, composite 304 has athickness of about 0.055 to 0.075 inches and weighs about 0.40-0.50lbs/foot² compared to a 0.040 inch aluminum liner panel that weighs 0.56lbs/foot². As with the wall panel described in FIGS. 7 and 7A, the wallpanel of FIGS. 17 and 17 a can also be used to form the thermalinsulated cargo trailer of FIG. 1A, van type trailer of FIG. 1C or otherthermal insulated enclosure.

While one or more preferred embodiments of the invention have beendescribed above, it should be understood that any and all equivalentrealizations of the present invention are included within the scope andspirit thereof. The embodiments depicted are presented by way of exampleonly and are not intended as limitations upon the present invention.Thus, it should be understood by those of ordinary skill in this artthat the present invention is not limited to these embodiments sincemodifications can be made. Therefore it is contemplated that any and allsuch embodiments are included in the present invention as may fallwithin the literal and equivalent scope of the appended claims.

1. A composite liner panel for use in a wall structure of a trailer,comprising: a first sheet having a length and a height; a second sheetforming a protruding surface over only a portion of the first sheet; andan adhesive coupling the first sheet and the second sheet.
 2. Thecomposite liner panel of claim 1 wherein the protruding surface acts asa scuff pad.
 3. The composite liner panel of claim 1 wherein the secondsheet extends substantially the height and the length of the firstsheet.
 4. The composite liner panel of claim 1 wherein the protrudingsurface protrudes away from the first sheet.
 5. A method for forming acomposite liner panel for use with a trailer, the method comprising thesteps of: a. providing a first layer and a second layer; and b. adheringthe first layer to the second layer, wherein the second layer includes aprotruding surface, along at least a portion of a height.
 6. The methodof claim 5, wherein a portion of the protruding surface acts as a scuffpad.
 7. The method of claim 5, after step (a) the step of eliminating aportion of the second layer.
 8. The method of claim 7, wherein one halfof the second layer is eliminated.
 9. The method of claim 5, wherein thecomposite liner panel is formed in a lamination process.
 10. The methodof claim 9, wherein the protruding surface is formed by the step ofproviding a shim layer to cover a portion of the second layer duringsaid lamination step.
 11. The method of claim 5, wherein the secondlayer extends substantially half the height of the first layer.
 12. Themethod of claim 5, further comprising the steps of: a. providing a thirdlayer and a fourth layer in an inverted orientation to the first layerand the second layer; and b. adhering the third layer to the fourthlayer while adhering the first layer to the second layer, wherein thefourth layer includes a protruding surface.
 13. The method of claim 12,further comprising the step of providing a fifth layer having the firstand second layers on one side of the fifth layer and having the thirdand fourth layers on another side of the fifth layer, the fifth layeracting as a release layer.
 14. The method of claim 5, wherein the secondlayer is provided as a laminated mat layer.
 15. The method of claim 14,further comprising the step of providing a plurality of laminated matlayers acting as a scuff pad.
 16. The method of claim 15, wherein thescuff pad is formed by the step of providing a shim layer to cover aportion of the plurality of laminated mat layers.
 17. The method ofclaim 15, wherein the plurality of laminated mat layers include theprotruding surface, the protruding surface protruding towards the firstlayer.
 18. A trailer comprising: a floor, a roof; and sidewallsextending vertically upward between the floor and the roof, thesidewalls comprising: at least one composite liner panel comprising: afirst sheet substantially the height of the trailer; a second sheetforming a protruding surface over only a portion of the first sheet; andan adhesive coupling the first sheet and the second sheet.
 19. Thetrailer of claim 18 wherein the protruding surface acts as a scuff padwithin the interior of the trailer substantially along the bottom of thetrailer.
 20. The trailer of claim 18 wherein the second sheet extendssubstantially the height of the trailer.
 21. The trailer of claim 18 thesidewalls further comprising an outer liner panel and an insulated coredisposed coplanar to the outer liner panel and the at least onecomposite liner panel.
 22. The trailer of claim 21 wherein theprotruding surface protrudes towards the insulated core.
 23. The trailerof claim 18 wherein the protruding surface protrudes towards theinterior of the trailer.
 24. The trailer of claim 23 wherein theprotruding surface extends along a length of the floor, wherein theprotruding surface acts as a scuff pad.